Update ReferenceProperty to generate subKey as a string to avoid errors where model shave to ID.
Update ReferenceProperty to generate subKey as a string to avoid errors where model shave to ID.

osric-the-knight/foam,shepheb/foam,foam-framework/foam,jacksonic/foam,foam-framework/foam,jlhughes/foam,foam-framework/foam,foam-framework/foam,mdittmer/foam,mdittmer/foam,osric-the-knight/foam,mdittmer/foam,osric-the-knight/foam,shepheb/foam,jlhughes/foam,jacksonic/foam,jacksonic/foam,jacksonic/foam,mdittmer/foam,foam-framework/foam,jlhughes/foam,osric-the-knight/foam,jlhughes/foam,shepheb/foam